Removal of color from real dyeing wastewater by Electro-Fenton technology using a three-dimensional graphite cathode

This work investigates the removal of color from wastewater that contains low dyestuff concentrations by the Electro-Fenton process. The color was removed by in situ electrogenerated hydrogen peroxides at a three-dimensional graphite cathode with added ferrous sulfates. Experimental runs were conducted to evaluate the effect of the operating parameters, such as the oxygen contact mode, the oxygen sparging rate, the applied current density, the concentration of ferrous ions, the solution temperature and the pH among others, on the removal of color. The removal efficiency of the color in the cathodic chamber reached 70.6% under specified operation conditions in 150 min. The removal efficiency was controlled by the mass transfer when the oxygen-sparging rate was less than 0.3 dm3/min for the reactor configuration herein. The optimal applied current density was 68 A/m2 when the energy consumption was considered. The highest removal efficiency was obtained by adding 20 mM Fe(II) to the solution. The optimal solution pH was 3 in this work. The temperature negatively affected color removal.